Traditional trailer bunks often use chemically treated 5.08 cm×10.16 cm (2 in×4 in) lumber that is covered with carpet. Mechanically attached to the treated lumber are wooden rails that extend partially along the legth of the boat trailer. These rails are typically covered with carpet in order to protect the hull of the boat that is being loaded onto the carpeted rails. The major drawback, however, of using carpeted rails and carpeted trailer bunks is that carpet begins to deteriorate after repeated exposures to water. Another disadvantage of this design is that the trailer bunk typically has a short life span since the chemically treated lumber and the wooden rails begin to decay after repeated use in an aqueous environment.
Other trailer bunks utilize chemically treated lumber with steel components that are mechanically attached to polymer rails. Polymer rails, unlike carpeted rails, do not deteriorate after repeated exposure to water. In addition to protecting the hull of the boat that is loaded onto the rail, the polymer rail also reduces the coefficient of friction between the boat hull and the rail thereby facilitating the loading and unloading of the boat onto the trailer. The disadvantage of this design, however, is that the steel components are susceptible to rusting after repeated exposure to water. Similar to the trailer bunk that is described in the preceding paragraph, this trailer bunk design also has a short life span because the chemically treated lumber, which is used as the base of the trailer bunk, begins to decay after repeated use in an aqueous environment.
Another drawback of traditional trailer bunk design is that they often have limited adjustability. Typically, the height of the trailer bunk is selected based on the anticipated bending stresses that are caused by the weight of the particular boat that will be loaded onto the trailer bunk. The angle of the trailer bunk's rail is determined by the shape of the particular boat's hull. Since these trailer bunks are secured by one or more bolts, which extend through one or more corresponding apertures on either side of the trailer bunk, the adjustability of the trailer bunk is limited because the location of the apertures are determined by the bending stresses that are exerted onto the trailer bunk as well as the dimensions of the boat's hull. In other words, a particular trailer bunk can only transport a boat having a specific weight and a specific hull design since the trailer bunk is designed only to accommodate a boat having those characteristics. If the boat trailer is to be used with a second boat having a different weight and a different hull design from the first boat, then a second set of trailer bunks would have to be used.
Because traditional trailer bunks are susceptible to decay and rust after repeated exposure to water and have a limited range of adjustability, there exists a need for an improved trailer bunk that has an improved life span as well as the ability to accommodate a variety of boat hull designs.